Humans first arrived in Australia by sea, through the islands now known as Indonesia and Papua New Guinea, many thousands of years ago. Estimates of the date vary considerably: the best current guess is about 53,000 years ago, but much room for debate remains.

The land that the first Australians colonised was very different to the Australia the first Europeans would see in the 18th Century: more timbered, greener, and with a wider variety of species. The long, slow desertification of the continent had been underway for millions of years, but with the arrival of humans it accelerated greatly. Fire, already a growing part of the Australian landscape, became much more frequent as hunter-gatherers used it as a tool to drive game, to produce a green flush of new growth to attract animals, and to open up impenetrable forest. Densely grown areas became more open sclerophyll forest, open forest became grassland. Fire-tolerant species became predominant: in particular, eucalypts, acacia scrub, and grasses. Long-lived and fire-intolerant species declined, as did woody shrubs and understory plants.

The changes to the fauna were even more dramatic, and much more rapid: not one species larger than a human survived, and many of the smaller species were wiped out too. All told, about 60 different vertebrates were exterminated, including the Diprotodon family (very large marsupial herbivores that looked rather like hippos), several large flightless birds, carnivorous kangaroos, a five metre lizard and a tortoise the size of a small car. The direct cause of the mass extinctions is uncertain: it may have been fire, hunting, or a combination of both, but there is no room to doubt that it was human intervention of one kind or another. (The once popular climate change explanation is no longer tenable. See Genyornis[?].) With no large herbivores to keep the understory vegetation down and rapidly recycle soil nutrients with their dung, fuel build-up became more rapid and fires burned hotter, further changing the landscape.

The eons-old trend to aridification of the continent reached a peak with the last ice age. The period from 18,000 to 15,000 years ago saw most of the continent become desert for a time. A number of mammal species, mostly rodents, arrived over the Indonesian landbridge. Roughly 13,000 years ago, that connection and the Bassian Plain between modern-day Victoria and Tasmania disappeared under the rising sea. From that time on, the Tasmanian Aborigines were isolated. Populations on small islands in Bass Strait died out completely. It is unknown if there were additional migrations by people from the north over the Indonesian land bridge during the last ice age. Linguistic and genetic evidence shows that there has been long-term contact between Australians in the far north and the Austronesian peoples of modern-day New Guinea and the islands, but that this appears to have been mostly trade with a little intermarriage, as opposed to colonisation.

At the time of European arrival in 1788, there were approximately half a million native Australians, forming hundreds of distinct cultural and language groups. Most were hunter-gatherers with rich oral histories and advanced land-management practices (the ecological destruction of the initial colonisation phase was thousands of years past). In the most fertile and populous areas, they lived in semi-permanent settlements. In the fertile Murray Basin, the gathering and hunting economies to be found elsewhere on the continent had in large part given way to fish farming. Little is known of the bulk of the Aboriginal peoples: European colonists, intent on carving a living from their harsh new land, paid little attention to them, and by the time anthropological investigation had become both fashionable and practicable, the only intact Aboriginal societies were those in very remote (and usually extremely arid) areas.

Between first European contact and the early years of the 20th Century, the Aboriginal population dropped from an estimated 500,000 to about one tenth of that number. Many were killed outright with gun, poison, or infected blanket, a great many more were starved to death by European conquest of their lands, but by far the most significant killer was European disease. Smallpox, measles, and influenza were major killers, many others added their toll - for a people without the thousands of years of genetically evolved resistance to diseases that Europeans had, even chickenpox was deadly. Of the 90% of the Aboriginal population that died out as a result of European contact, it is estimated that around 80 or 90% of the deaths were the result of disease, and reasonable to suppose that the worst-hit peoples were the ones that lived in the most fertile areas, where population densities were highest.

After the loss of the United States, Britain felt a need to find an alternative destination to take the population of its overcrowded prisons (full mainly due to the unemployment created by the Industrial Revolution) and needed somewhere to send their overflow: the the newly discovered land was considered the best option. In 1777 the First Fleet of 11 ships and about 1350 people under the command of Captain Arthur Phillip set sail for Botany Bay[?]. On arrival, Botany Bay was considered unsuitable and on January 26, 1788—a date now both celebrated and mourned as Australia Day)— a landing was made at the nearby Sydney Cove[?]. The new colony was formally proclaimed as the Colony of New South Wales on February 7. Thus European settlement began with a troupe of petty criminals, second-rate soldiers, and a crew of sailors. While reasonably well-equipped, little consideration had been given as to the skills required to make the colony self-supporting - virtually none of the convicts had farming or trade experience (nor did the soldiers, for that matter), and the lack of understanding of Australia's seasonal patterns saw initial attempts at farming fail, leaving only what animals and birds the soldiers were able to shoot. Some relief arrived with the Second Fleet in 1790, but life was extremely hard for the first few years of the colony.

Convict life was harsh, equivalent to what would by 20th century standards be considered a concentration camp (and, in terms of relative remoteness to the inmate's homes and families, a concentration camp on Mars). Convicts were assigned to work gangs to build roads, buildings, and the like. Female convicts were usually assigned as domestic help to soldiers.

By 1790, convict James Ruse[?] had begun to successfully farm near Paramatta[?], the first successful farming enterprise, and he was soon joined by others. The colony began to grow enough food to support itself, and the standard of living for the residents gradually improved.

much more about early history, including rum rebellion, beginning of free settlers, wool, the French ship that almost claimed us etc.*

The mid-19th century saw the beginning of government policies to emancipate convicts and assist the immigration of free settlers. The discovery of gold in 1851 led to a boom in population, wealth, and trade, and after a prolonged agitation, transportation of convicts ended completely soon after.

In the 1890s, economic depression (the most severe Australia had ever faced) made the inefficiencies of the six colonies seem ever more ridiculous, and, particularly in border areas, a push for an Australian Federation began. Several referenda on the issue were held, the third attempt finally passing in 1897 (?). Discussions between Australian and British representatives led to adoption by the British Government of an act to constitute the Commonwealth of Australia in 1900.

Melbourne was chosen as the temporary seat of governmemt while a purpose-designed capital city, [Canberra]], was constructed. The future King George V, then the Duke of York, opened the first Parliament on May 9, 1901, and his successor, (later to be King George VI) opened the first sesson in Canberra during May 1927. Australia became officially autonomous in both internal and external affairs with the passage of the Statute of Westminster Adoption Act on October 9, 1942. The Australia Act[?] in (1986) eliminated the last vestiges of British legal authority at the Federal level. (The last state to remove recourse to British courts, Queensland did not do so until 1988).

Australia sent many thousands of troops to fight for Britain in World War I. Thousands lost their lives at Gallipoli, on the Turkish coast.